In many industrial installations, a large supply of water is often needed for cooling, flushing, or other applications. Such a large supply of water is usually taken from a body of water, such as a river, stream, pond or other water source, which contains particulate material, such as leaves, twigs, stones and the like, that would be harmful to industrial equipment and which particulate material must be removed. In order to remove such particulates, an initial bar screen may be used to filter out the largest articles, while other particulates are fed to a straining apparatus which may be a rotary strainer containing a rotary basket screen or other device to remove particulates.
The assignee of the present invention has, for example, provided strainers which are adapted for service on a suction side of pumps to strain liquid of foreign matter, and one such device is of a motorized self-cleaning type that contains a strainer basket in a housing, which basket is motor driven. A support with spokes suspends the strainer basket in the housing, while a brush, shear knife and/or water jet device is used to clean the strainer basket sidewall. A revolving brush on the outside of the strainer basket keeps the strainer basket openings free from clogging, while a shear knife on the outside of the strainer basket shears any protruding matter from the basket as it revolves, and high pressure cleaning jets pressure clean the strainer basket as it revolves, forcing debris from the strainer basket and its openings. While this type of device is eminently suited for most applications, the support and spokes are positioned in the flow of water containing particulates and collection of debris thereon or wearing of the same by contact with the particulate-containing water would best be avoided.
In co-pending application Ser. No. 748,659, now U.S. Pat. No. 5,183,568 of which this application is a continuation-in-part, a self-cleaning strainer is described having a vertically disposed housing which contains a rotatable strainer basket. The housing has an open top, closed by a closure plate, an inlet adjacent the top of the housing and an outlet adjacent a closed bottom of the housing, the closed bottom having a flush discharge opening. The components used to rotate the strainer basket are disposed outside the flow of any water containing particulates that enters the housing. Cleaning devices, such as a scraper blade supported in the strainer basket, a rotatable brush supported in the strainer basket, and a water jet manifold disposed between the housing sidewall and the sidewall of the strainer basket are used to clean the rotatable strainer basket.
It is an object of the present invention to provide a self-cleaning strainer where the apparatus used to rotate the strainer basket is positioned out of the flow of liquid containing particulates that is fed to the strainer basket.
It is another object of the present invention to provide cleaning devices for the wall of the strainer that better act to clean the openings and inner surface of the wall of the strainer basket.
It is yet another object of the present invention to provide a self-cleaning strainer having a combination scraper-backwash unit that enables adjustable backwashing of the inner surface of the wall of the strainer basket without the use of water-jet sprays.
It is a further object of the present invention to provide for intermittent rotation of a brush that is adapted to clean the inner surface of the wall of the strainer basket.